Kilauea

United States

19.421°N, 155.287°W; summit elev. 1222 m

All times are local (unless otherwise noted)

On 23 April inflation occurred at Pu`u `O`o , with no change in seismicity at Kilauea. Observations on the 24th revealed that the January 2002 cone continued to emit lava onto the Pu`u `O`o crater floor. During 24-29 April, no surface lava was visible on Pulama pali. Fairly rapid deflation occurred on the 28th. During the report period, tremor at Pu`u `O`o was at low levels, and only a few small earthquakes and low-level tremor occurred at Kilauea's caldera.

Geologic Background. Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.